Hypohalites, decomposition

As anticipated, the W-halosuccinimides (50) and alkyl hypohalites are reactive toward trivalent phosphorus compounds. The biphilic mechanism for hypohalite decomposition has been clarified using optically active phosphines (51,52). 

The homolysis of tertiary hypochlorites for the production of oxy radicals is well known." The ease with which secondary hypohalites decompose to ketones has hampered the application of hypohalites for transannular reactions. However the tendency for the base-catalyzed heterolytic decomposition decreases as one passes from hypochlorites to hypobromites tohypoidites. Therefore the suitability of hypohalites for functionalization at the angular positions in steroids should increase in the same order. Since hypoidites (or iodine) do not react readily with ketones or carbon-carbon double bonds under neutral conditions hypoiodite reactions are more generally applicable than hypochlorite or hypobromite decompositions. 

Such solutions are necessarily contaminated with halide ions and with the products of any subsequent decomposition of the hypohalite anions themselves. Alternative routes are the electrochemical oxidation of halides in cold dilute solutions or the chemical oxidation of bromides and iodides ... 

The manner and rate of decomposition of hypohalous acids (and hypohalite ions) in solution are much influenced by the concentration, pH and temperature of the solutions, by the presence or absence of salts which can act as catalysts, promotors or activators, and by light quanta. The main competing modes of decomposition are ... 

It is especially prone to explosive decomposition. Use at vapour pressures above 30 mBar is not advised. It is a strong oxidiser. An improved preparation is described. See entry BIS(FLUOROOXY)PERHALOALKANES See other HYPOHALITES... 

The hypoiodite ion is much less stable than the other hypohalite ions, decomposing almost completely to iodate and iodide in a few hours, whereas the corresponding decomposition of hypochlorite at the same concentration and the same temperature requires several years. 

MEK evaporates readily into the atmosphere and is subject to rapid photochemical decomposition. It reacts to form a haloform that is more toxic than the original compound in water containing free halogens or hypohalites. MEK does not accumulate in any environmental compartment, and it is rapidly metabolized by microbes and mammals. There is no evidence of bioaccumulation. 

Diazirine was used as the carbene precursor in an experiment to make diazomethane from methylene and nitrogen in the gas phase. As shown by means of labeled nitrogen, there was 4% diazomethane formation. During the past 10 years thermal as well as photochemical decomposition of 3-chloro- and 3-bromodiazirine has been investigated in detail. Compounds 175 and 176 as well as analogous compounds are easily obtained by reaction of amidines with hypohalites according to Graham. ... 

The primary products of the Hunsdiecker reaction are probably the hypothetical acyl hypohalites that later undergo radical decomposition ... 

The other hypohalous acids are all very reactive oxidizing agents that are relatively unstable. They are most conveniently prepared by the disproportionation of the parent halogen, X2, in water [Eq. (14)]. Addition of HgO or Ag20 precipitates the halide ion and shifts the equilibrium so as to favor additional hypohalite formation. Attempts to prepare pure samples from aqueous solution lead to decomposition. 

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